# design 7 V-G1: grey zone, VM. tc netem delay 400ms on one legacy instance; health check passes, /api/price p95 breaks. Correct: mig.recreate_instance after approval.
id: V-G1
path: gray
asset: vm
expected_layer: 2
ground_truth_label: network_latency_legacy
ground_truth_action: mig.recreate_instance
description: tc qdisc add dev ens4 root netem delay 400ms on the legacy instance that currently serves the api traffic (legacy:busy)
# 2026-10-08: the ILB hashes the api pods' few keep-alive connections onto one instance; in campaign 2 legacy:0 served 0 rps,
# so the delay was never on the request path. legacy:busy = the instance with the most legacy-api requests over the last
# 2 minutes (Mimir); the harness caches the choice per scenario so the revert hits the same instance.
inject:
  method: ssh
  host: legacy:busy
  command: sudo tc qdisc replace dev ens4 root netem delay 400ms
revert:
  method: ssh
  host: legacy:busy
  command: sudo tc qdisc del dev ens4 root || true